Guys the water you retain with high estrogen will cause some cause strength gains, but if you are talking about muscle gains, then no, estrogen does not help.
Example: I'm on week 5 of 750 mgs/wk of test e and I take 1.25 mgs a DAY of letro. I've went from 235 lbs. to 250 lbs. and lost fat at the same time. All I'm on it test keep in mind.